After more than 45 years in operation, many installations in the storage power stations operated by Kraftwerke Hinterrhein AG (KHR) have reached the end of their technical lives. The largest hydropower complex in the canton of Graubünden is now to undergo a major overhaul. KHR will equip the three power stations with state-of-the-art technology, comprehensively overhaul the machine groups, and replace generator stators and turbine wheels in order to increase efficiency.
Corrective maintenance on the reservoirs and equalising reservoirs as well as renovations to pressure pipes, plating and orifice floodgates will also help to enhance efficiency. Kraftwerke Hinterrhein AG expects to increase efficiency by around three percent, resulting in a rise in annual production of some 40 GWh.
On average the complex, which was built between 1956 and 1963 and has a collective installed capacity of 650 MWH, generates 1,410 GWh of electricity per year. To ensure its operating safety and profitability until the licence expires in 2042, KHR has decided to completely renovate the complex. With this in mind, the company intends to invest around CHF 275 million between 2011 and 2017.
Renovations all in one go
The scale of the renovation work is on a par with the original construction project back in the 1950s. Renovations to the shafts and buildings as well as the hydraulic and electrical equipment across all three levels of the power station will be carried out "all in one go". Due to the water conditions, most of the work will be performed in the winter. To minimise the impact on the environment and population, the project will be environmentally monitored.
Reservoirs drained for the first time
To enable all the work to be carried out, KHR drained the Valle di Lei, Sufers and their equalising reservoirs Bärenburg, Ferrera and Preda in the winter of 2012/2013, for the first time in their history. The drainage of these man-made lakes was planned in collaboration with the cantonal offices, fisheries association and environmental organisations. Once all the work is completed, targeted measures will be carried out to replenish the fish stocks.
The following parties hold a stake in Kraftwerke Hinterrhein AG: Edison SpA (20%), the City of Zurich and Axpo Power AG (19.5% each), the canton of Graubünden (12%), Alpiq (9.28%), BKW (7.72%), Repower (6.5%), the licensing municipalities (3%) and IWB (2.5%).
Source: Kraftwerke Hinterrhein AG website, www.khr.ch